1 Rules to override:
1) The "Return value type method name (parameter list)" of the subclass method must be the same as the parent class method
2) The modifier of the subclass method cannot be less than the modifier of the parent class method
3) If the parent method throws an exception, the subclass method throws an exception type that cannot be greater than the parent class
4) The Child parent class method must be either static or non-static
5) The method of private in the parent class cannot be overridden because it is not visible to the child class. You can define the same method name in a subclass, different methods that return a value type, but are not overridden. In addition, other subclass methods that are the same as the parent method name return a value type, and the argument list must be the same.
Override of method (override overwrite)